Electric motor.



No. 881,585. PATBNTED MAR. 10, '1908. B. HOPKINSON & J. FRITH.

ELECTRIC MOTOR.

APPLICATION FILED nno. 29 1905.

3 SHEETS-SHEET 1.

J m w .1 I Z w Z L 1 No. 881,585. PATENTED MAR. 10, 1908. B. 'H OPKINSON & J. FRITH.

ELEOTRIO- MOTOR.

APPLIOATION FILED DEO.29.1905.

3 $HBETSSH BBT 2.

No. 881,585. PATENTED MAR. 10, 1908.

E. HOPKINSON & J. FRITH. 1

ELECTRIC MOTOR.

APPLICATION FILED DEG. 29,1905.

3 SHEETSSHEET .ZQwanZmu UNITED sTATEs PATENT oFFroE.

EDWARD HOPKINSON AND JULIUS FRITH, OF MANCHESTER, ENGLAND, ASSIGNORS TO MATHER & PLATTLIMITED, OF MANCHESTER, ENGLAND.

ELECTRIC MOTOR.

To all whom it may concern:

Be it known that we, EDWARD HOPKINSON and JULIUS FRITH, subjects of the King of Great Britain and Ireland, residing, respectively, at -Ma'nchester, England, have invented Im rovements in Electric Motors, of which the "ollowing is a s iecification.

This invention has re erence to improvements in electric motors. An electric motor according thereto comprises a olurality of rotors and an electro-magnetic 1eld sys tem common to and adapted to simultaneously rotate the said rotors.

According to one construction, the electric motor is of the induction type, actuated by polyphase electric currents, and comprises a stator having two fixed and opposite y arranged parts between which are arranged a plurality of rotors that can be caused to rotate at the same speed or at different speeds. The two parts of the stator may be rectilinear, and in that case may be parallel or inclined to each other; or they may be segmental or they may form two complete concentric circles with the rotors arranged in an annular space or row between them. It is preferred to construct the two parts of the stator, which may be mechanically connected by cross stays, from superposed stamping-s of iron or steel having teeth which project inwardly but are arranged to leave a space between the two stators for each rotor. Through the slots between the teeth of the superposed stampings are wound. insulated conductors supplied with polyphase currents from an external source, the electrical con-- nections being arranged in such manner that the moving magnetic field induced by the polyphase currents will progress in opposite directions in the two parts of the stator.

In the space left between the inwardly projecting teeth of the two parts of the stator, which constitute the magnetic poles,

are placed a pluralityof rotors, with their axles arallel or ap )roximately so, and arranged at right angles or approximately so, to the plane of the stator and carried in suitable supports. Theserotors may be solid or tubular, and may have smooth surfaces, or their surfaces may be grooved or slotted, and conductors may be placed in the grooves or slots, as heretofore usual in induction motors Since the moving magnetic field in the Specification of Letters Patent.

Application filed December 29, 1905.

Patented March 10, 1908.

Serial No. 293,761.

part .of the stator on the one side of the rotors is progressing in the reverse direction to that in the part of the stator on the other side, electric currents will be induced in the rotors between them, or in the coils thereon, which will cause the rotors to rotate at a uni form s )eed proportional to the frequency of the polyphase currents in the stators, since the moving field is common to all the rotors. The speed of progression of the moving magnetic field may be varied by varying the frequency of the polyphase currents in any convenient manner, whereupon the speed of rotation of the rotors will simultaneously Vary in like proportion.

By a modification in the construction, according to which the pitch of the poles of the two stators, or in other words the distances from one pole to the next, is made different at different parts of the stators, the rotors placed in such different parts will be caused to rotate at different speeds, which will be in exact ratios, corresponding to the pitch of the poles.

The invention furtherconsists in the varioiis novel features of construction and in the combinations and arrangements of parts all as hereinafter more particularly described and pointed out in the claims.

In the accompanying illustrative drawings Figure 1 shows in plan, part of an electric motor according to this invention, having a rectilinear stator. Fig. 2 is a sectional elevation on the line A A of Fig. 1. Fig. 3 showsin plan, part of an electric motor according to this invention constructed with a curved stator, the stator windings being omitted. Fig. 4 is an elevation of a single rotor but without the conductors or windings shown in Figs. 1 and 2. Figs. 5 and 6 show, diagrammatically, modified constructions.

a and b are the two oppositely arranged parts of the stator built up of superposed stai'npings of iron or steel formed with slots 0 and with intervening teeth (1, constituting the poles, which project inwardly or towards each other and are made of such length as to leave spaces between them for the reception of the rotors e. At those places where no rotors are to be mounted, the teeth from the opposite stators may be continued and thus caused to constitute cross stays, as at d. The stampings composing the two parts of the stator may be further held together by screw\ threaded rods 9 that pass through them and through cross stays h and are provided with nuts 'i between which the stampings can be tightly clamped. The cross stays k may also, as shown, be utilized to carry thebearings for the axles k of the rotors e.

Insulated conductors m are wound in the ordinary way in the slots 0 between the teeth (1 and d of the stator to form the stator windings which are traversed by polyphase electric currents supplied, as usua from an external source, whereby a moving magnetic field will be induced in the stator in a manner well understood. The windings m are, however, according to this invention, connected and arranged in such manner that the moving magnetic field set up in the part a of the stator will progress in the opposite direction to that simultaneously set up in the part b of the stator, that is to say, if the field set up in the part a progress in the direction of the arrow as, that set up in the part b will progress in the direction of the arrow y. For this purpose, a single set of polyphase windings m may be arranged to extend in one direction along one part of the stator and then be bent round and arranged to extend backward or in the opposite direction along the other part of the stator.

The form of the stators may, as hereinbefore stated, be rectilinear, as shown in Figs. 1 and 6; or segmental, as indicated in Fig. 3; or its two parts may form two complete circles arranged concentrically one within the other, asindicated partly y the full and partly by dotted lines in Fig. 5.

The rotors e, which, as stated above, are mounted torotate in the spaces left between the teeth d, (1, may be of any of the well known forms of construction used in induction motors, and may be solid or tubular; they may also be provided with conductors wound on them, or arranged in slots formed in their periphery; and these windings may be of the so-called s uirrel-cage type, or they maybe provide -with slip-rings, as well understood. In the examples illustrated, the rotors are each provided with a winding n of the squirrel-cage type.

Since the direction of progression of the moving magnetic field in the part a of the stator is opposite to that in the part b of the stator, electric currents will be induced in all the rotors '6 between them, and the rotors will thereby be caused to rotate simultane ously. If the pitch of the magnetic poles, that is to say the number of poles per rotor, be equal, as in the exam les shown in Figs. 1, 2 and 3, the rotors wi l rotate simultaneously at a uniform speed which will be proportional to the frequency of the polyphase currents sup lied to the stator windings since the movmg magnetic field is common to all the rotors. The speed of progression of the moving magnetic field in the two arts of the stator may be varied by any 0? the well known methods, such as by altering the frequency of the polyphase currents, or by alterin the connection of the windings m by a suitahle switch, whereupon the s eed of rotation of the rotors will be simultaneously varied in like proportion.

By the modified form of construction shown in Fig. 5, according to which thepitch of the magnetic poles formed by the sets of teeth 0 is made different at different parts of the stators a and b, it is possible to obtain simultaneously different seeds of rotation for the rotors e placed in t ese different parts, such different speeds being in exact ratios corresponding to the pitch of the poles. In the example shown, the two parts a, b of the stator. have two, four, six and eight poles per rotor e at the positions 1, 2, 3 and 4 respectively so that the speeds of the rotors at these ositions will be in the ratio of one, one hal one third and one quarter,

there being three windings m for a three phase current.

In the arrangements shown in Figs. 1, 3 and 5, the rotors e are all of the same diameter. When the two parts a, b of the stator are rectilinear and are inclined to one another, as shown in Fig. 6, the rotors 0 may be made of successively'lar er and larger diameter from near one end 0 the two parts of the stator towards the other end.

It will be evident that various other chan es can be made in the construction of the e ectric motors without departing from the spirit and scope of the invention so long as the relative arrangement of the main parts of such motors, or the mode of operation described, is retained.

An induction motor constructed as described is adapted for use in any case where it is desired to provide a motor of compact.

comprising a plurality of independent rotors mounted to revolve about separate axes displaced laterally of one another, and a stationary electro-magnetic system common to and arranged to extend symmetrically around said rotors in a direction transverse to their axes and to act inductively and equally upon diametrically opposite parts of each rotor and to simultaneously rotate all the rotors.

3. An electric motor of the induction type comprising a plurality of independent rotors mounted to rotate about separate axes, and a stationary electro-magnetic system common to said rotors and having .polyphase windings arranged to produce magnetic holds that travel in reverse directions in opposite arts of said electro-magnetic system am to act inductively upon and simultaneously rotate said rotors.

4. An electric motor of the induction type comprising a plurality of rotors revoluble independently about separate axes, and a stator comprising oppositely arranged parts common to all the rotors, the rotors being arranged between the parts of the stator and the stator being provided with polyph ase windings arranged so that a moving mag nctic field set up in one part of the stator will be caused toprogress 1n the reverse direction to that setup in the opposite part of the stator.

5. An electric motor of the induction ty e comprising a stator having two op osite y disposed parts provided with po.yphase windings producing op ositely movin magnetic fields therein, am a pluralityo? independent rotors, revoluble about separate axes and arranged between the parts of said stator.

6. An electric motor of the induction type comprising a stator having oppositely disposed arts in which 0 positely moving magnetic fields are pro uced, polyphase windings producing such fields, and a plurality of rotors arranged symmetrically between the parts of said stator and revoluble about axes which are independent and arallel or substantially parallel to one anot ier.

7. An electric motor of the induction type comprising a stator having parts arranged parallel to one another and provided'with polyphase windings producing oppositely moving magneticfields, and a row of rotors arranged between the arts of said stator and independently revo uble about separate axes.

8. An electric motor of the induction type comprising a stator having oppositely arranged parts that are providedwith polyphase windings and are of curved shape in the direction of their length, and a plurality of independent rotors arranged between the parts of said stator and revoluble about sepa rate axes located in a curved line.

9. An electric motor of the induction type comprising a stator having two annular parts arranged concentrically in the same plane.

and provided with p olyphase windings prowinding and sets of magnetic poles of differ ent pitch, and a plurality of independently revoluble rotors arranged between said sets of poles.

12. An electric motor of the induction type comprising a stator having two op ositely arranged parts provided with po y phase windings and connected together at intervals, anda plurality of rotors independently revoluble located between said parts of the stator.

13. An electric motor of the induction type comprising a stator having two slotted parts arranged o posite each other in a com- 7 mon plane, an provided with polyphase winding, and a plurality of independent rotors arranged between said parts of the stator with their axes in separate planes at right angles to that of the stator.

14. An'electric motor of the induction type comprising a stator having two slotted parts arranged in a common plane and provided with polyphase windings roducing oppositely moving magnetic fields mthe two parts, cross stays connecting said parts of the stator together at intervals of their length, a plurality of independent rotors arranged between said parts of the stator and cross stays, and bearings carried by said parts of the stator for said rotors.

15. An electric motor of the induction type com rising two stators built 11 of superpose slotted laminae arranged to Form circular sets of magnetic poles in a common plane, polyphase windings extending through the slots in said stators, cross stays integral with said laminae and connecting said parts of the stator together at intervals of their length, and a plurality of independent rotors loclated between the circular sets of magnetic 0 es. p 16. An electric motor of the induction type comprising a stator having two horizontal parts 'formed of plates slotted to form sets of oppositely arranged bars or teeth in a common plane, some of which extend across from one stator to the other, polyphase windings extending through the slots between said teeth so as to produce oppositely moving magnetic fields in the two parts of the stator, a plurality of independent rotors tine of Lancaster, England, this seventh day arranged between the sets of teeth with their of December 1905.

axes vertical and parallel to one another, EDWARD HOPKINSON. and upper and lower bearings, connected to JULIUS FRITH.

5 the upper and lower sides of the parts of said Witnesses:

stator, for said rotors. ROGER E. GRIME,

Signed at Manchester, in the county pala- GEORGE P. SIMPSON. 

